Inductive loads can be used to enhance the bandwidth of circuits, such as amplifiers and buffers, which include the inductive loads. In these circuits, an inductive load exhibits an increase in impedance, referred to as inductive peaking, that is related to an increase in the operating frequency of the circuit that includes the inductive load. Inductive peaking in the inductive load extends the operating frequency range or bandwidth of the circuit that includes the inductive load.
An inductive load can be implemented in an integrated circuit as a passive spiral inductor or as an active inductive load. Often, a spiral inductor is large and, once designed, has a useful frequency range that cannot be changed very easily. In contrast, an active load with inductive peaking is small and has an operating frequency range that can be made programmable very efficiently.
Typically, an active inductive load requires a large voltage drop across the load with respect to the power supply voltage. This large voltage drop is subtracted from the power supply voltage to arrive at the headroom available for operation of the circuit that includes the inductive load. As power supply voltages drop, large voltage drops across active inductive loads become problematic, in that headroom decreases and the circuit that includes the active inductive load may cease to function reliably.
For these and other reasons there is a need for the present invention.